The rate of U.S. adults without health insurance jumped in the first quarter of 2017, as the Trump administration worked to repeal Obamacare and replace it with its own health-care reform bill.

The latest Gallup-Healthways poll found that 11.3 percent of U.S. adults didn't have health insurance in the first quarter of the year, compared to 10.9 percent of adults uninsured in the third and fourth quarters of 2016.

"The slight rise in the number of uninsured Americans in the first quarter of 2017 could, in part, be attributable to the uncertainty surrounding the long-term future of the Affordable Care Act," wrote Gallup's Zac Auter. "As such, it will be important to monitor the uninsured trends in the coming months as these events unfold. If coverage options and premiums do change, members of Congress from both parties may show a renewed urgency to address the healthcare issue."

Despite the increase Gallup found in its survey, the rate of adults without insurance remains well below a peak hit in the third quarter of 2013, when 18 percent of U.S. adults lacked health insurance, according to the researcher's data. This was right before health insurance exchanges authorized under President Barack Obama's Affordable Care Act, or Obamacare, were opened nationwide in October 2013.

Since 2013, the percentage of uninsured young adults has dropped sharply since 2013 — largely due to a provision that allows individuals the ability to stay on a parent's plan until turning 26. Also, there is a requirement that most Americans have health insurance or face a tax penalty.

That trend is key because young adults tend to be healthier than older adults, and typically pay more in health-care premiums than insurers need to pay out for medical costs.

With President Donald Trump in the White House, the future of this health-care legislation remains unsettled. Republicans would still like to repeal and replace the ACA, but it's unclear how soon House Speaker Paul Ryan will be able to rally enough support.

Amid the uncertainty, several major insurers have already announced they are abandoning some health exchanges for 2018 plans, implying coverage options could dwindle further, and premiums could rise even higher across the U.S.

U.S. adults without insurance (%)

Source: Gallup-Healthways poll

The Congressional Budget Office projected earlier this year that Republicans' health-care proposal — before being yanked from consideration — could have led to 14 million fewer people having health insurance in 2018, and 24 million fewer insured Americans by 2026 than would be covered if Obamacare remained intact.

Ryan has since refused to commit to a timeline for a new version of the GOP's health-care reform strategy, but Trump has made it clear he still wants Obamacare replaced, saying he wants to make it "a good deal," not "a bad deal."

Since November 2016, Gallup found all partisan groups have become more supportive of Obamacare, including a 10-point increase among Republicans and a 17-point jump among independents.

The results for Gallup's poll were based on 44,596 interviews with U.S. adults aged 18 and older from Jan. 2 to March 31, conducted as part of the Gallup-Healthways Well-Being Index. Gallup and Healthways have asked a random sample of at least 500 U.S. adults each day since January 2008 whether they have health insurance.